1. Field of the Invention
The present invention relates to food products and, more particularly, to presweetened ready-to-eat breakfast cereals. In its method aspect, the present invention relates to methods for the preparation of presweetened food products such as ready-to-eat cereals.
2. The Prior Art
Presweetened breakfast cereals have been regularly available for many years. Such cereals have been prepared by first producing unsweetened cereal pieces, particularly puffed cereal pieces, coating the cereal pieces with a slurry or solution of sweeteners and then drying the coated pieces in an oven or air current.
Generally, the primary sweetener for presweetened cereals has been sucrose. Sucrose solutions frequently contain various levels of regular (e.g., 42 D.E.) corn syrup to provide upon drying coatings which are either desirably clear or frosted.
While effective to sweeten cereals, attempts for nutritional reasons have recently been made to reduce the sucrose and/or total sugars content of presweetened cereals. To provide traditional levels of sweetness at reduced concentrations, sweeteners having more sweetening power per unit weight than sucrose (i.e., having higher relative sweetness) must be employed. While certain high potency non-nutritive or "artificial" sweeteners have been suggested for use, both current food regulations and strong consumer prejudice against artificial sweeteners have directed art attempts at providing presweetened cereals employing only nutritive carbohydrate sweetening agents.
Since fructose is 10%-70% sweeter than sucrose, art attempts have been to employ fructose as a sweetening agent for ready-to-eat cereals. Fructose is commercially available in basically two forms, (1) high fructose corn syrup, (hereinafter "HFCS") normally a liquid, (20% moisture) and (2) crystalline fructose which is a solid powder.
High fructose corn syrup has the advantage of being relatively inexpensive compared to crystalline fructose. Employment of HFCS as the principal component of coating for presweetened cereals, however, suffers from several disadvantages. First, coating cereals with HFCS result in a sticky, messy product which at best is extremely difficult to dehydrate to a solid, non-adhesive state. However, at least one method is known within realizes an R-T-E cereal coated with corn syrup by applying a powder coating to eliminate the stickiness (see U.S. Pat. No. 4,089,984 issued May 16, 1978 to Gilbertson, and which is incorporated herein by reference).
Another problem with HFCS is that it is not as sweet as crystalline fructose. Fructose exists mostly in four forms as the alpha-furano, beta-furano, alpha-pyrano and beta-pyrano structures. The sweetness perception of fructose is, however, primarily a function of the amount of the beta-pyrano form. Crystalline fructose, is usually manufactured as theoretically pure anhydrous beta-D-fructopyranose for this reason (although typical analysis indicate only 97.2% beta-pyranose). HFCS, on the other hand, is not as sweet as pure crystalline fructose since it is an amorphous mixture of these non-sweet fructose forms as well as the sweet form and it contains also less sweet glucose. HFCS comprises only about 57-70% of the sweet beta-pyrano form (basis on total fructose). Therefore, crystalline fructose is substantially sweeter on a unit weight basis than HFCS (dry basis).
Accordingly, it would be desirable to be able to transform all or part or "beneficiate" the amorphous mixture of fructose forms which comprise HFCS into the sweet beta-pyrano form to increase the sweetness of the HFCS. Unfortunately, the known properties of fructose suggest that adding crystalline fructose to corn syrup would result in the reverse conversion, that is, the degradation of the crystalline fructose into a mixture including the non-sweet forms rather than the beneficiation of the amorphous HFCS into more sweet forms. It is known that a freshly prepared solution of beta-D-fructopyranose undergoes a transformation called mutarotation to the other forms resulting in a less sweet mixture, HFCS is such a mutarotated or "amorphous" mixture containing only about 57-70% beta-pyranose depending on temperature and concentration. (See, for example, "Encyclopedia of Food Science", pg. 330, ed. by Peterson and Johnson, The Avi Publishing Co., Inc., Westport, Conn. See also U.S. Pat. No. 4,277,504, issued July 7, 1981 to K. A. Kurzins). Adding more pure crystalline fructose to HFCS would not be expected to alter the percentage of the beta-pyrano form since in a short time the pure beta-pyrano form will mutarotate into the amorphous mixture.
It has been surprisingly discovered, however, that by combining crystalline fructose of a particular particle size and HFCS seeded with the powdered crystalline fructose within a certain weight ratio range, that the non-sweet forms of fructose of the HFCS can be converted in situ into the more sweet forms. Accordingly, food products can be prepared with sweetener coatings containing fructose having the sweetness of pure crystalline fructose but formulated with partial replacement of the crystalline fructose with the less expensive HFCS.
Surprisingly, another advantage provided herein by the in situ conversion of amorphous fructose into crystalline fructose on cereal coatings is to reduce the undesirable hygroscopicity of the coating. Reduced hygroscopicity beneficially reduces undesirable clumping or bridging of coated cereal pieces.